Recently, in portable electronic devices, virtual reality devices, remote-controlled manipulators, training simulators, and the like, vibration actuators are provided to provide various vivid haptic feedbacks to users.
In the vibration actuators, there are various types such as an eccentric rotating mass (ERM), a linear resonant actuator (LRA), a piezoelectric element actuator, and an electroactive polymer actuator.
Among them, the LRA generates the vibration by reciprocating a vibration mass connected to the permanent magnet linearly by inductive magnetic force of the coil and has been most widely used because a response speed is fast, the power consumption is low, and the durability is excellent as compared with an ERM.
However, in the conventional LRA, since a vibration frequency is limited to a resonance frequency of the vibration mass, it is difficult to provide various haptic feedbacks.
[Prior Art Document] Korean Patent No. 10-1597026 (issued on Mar. 7, 2016)